The purpose of a vehicular transmission is to provide a neutral, at least one reverse and one or more forward driving ranges that impart power from an engine, and/or other power sources, to the drive members which deliver the tractive effort from the vehicle to the terrain over which the vehicle is being driven. As such, the drive members may be front wheels, rear wheels or a track, as required to provide the desired performance.
Although a wide variety of transmission types are available, transmissions adapted to receive the output power from either an engine or an electric motor, or both, can be provided that will operate at high efficiencies over a wide variety of operating conditions. One transmission in the nature of a two-mode, input-split, parallel, hybrid electro-mechanical transmission is deemed to be particularly suitable to receive power from a vehicle engine and a power output member to deliver power to drive the vehicle. First and second motor/generators are connected to energy storage devices, such as batteries, so that the energy storage devices can accept power from, and supply power to, the first and second motor/generators. A control unit regulates power flow among the energy storage devices and the motor/generators as well as between the first and second motor/generators.
A variable, two-mode, input-split, parallel, hybrid electro-mechanical transmission also employs at least one planetary gear set. The planetary gear set has an inner gear member and an outer gear member, each of which meshingly engages a plurality of planet gear members. The input member is operatively connected to one of the gear members in the planetary gear set, and means are provided operatively to connect the power output member to another of the gear members in the planetary gear set. One of the motor/generators is connected to the remaining gear member in the planetary gear set, and means are provided operatively to connect the other motor/generator to the output shaft.
One particularly suitable arrangement is disclosed in copending U.S. patent application, Ser. No. 09/103,850 (Attorney Docket No. H-201729), filed Jun. 24, 1998, now U.S. Pat. No. 5,931,757, and which has also been assigned to General Motors Corporation. In that transmission the planetary gear arrangements, as well as the two motor/generators, are coaxially disposed and the motor/generators are each configured as an annulus which circumscribes one or more of the planetary gear arrangements such that the planetary gear arrangements are disposed radially inwardly of the motor/generators.